Supervolcanoes​

Resources - To access the Google Drive Folder with the main tasks and resources for the supervolcanoes section click here.

Specification - Supervolcanoes are on a much bigger scale than other volcanoes, and an eruption would have global consequences. ​The characteristics of a supervolcano and the likely effects of an eruption.

Linking the Learning- The questions below are examples that have appeared on pas IGCSE and GCSE examintion papers.​

Videos- The following video illustrate the characteristics and possible short and long term effects of a supervolcano eruption.​​

General Information- Supervolcanoes volcanoes are on a much bigger scale than volcanoes. They emit at least 1,000 km2 of material - compare this with an eruption on the magnitude of Mt St Helens in 1980, which emitted some 1km2. The diagram below illustrates the magnitude of some different eruptions.​

Supervolcanoes do not look like a volcano with its characteristic cones. Instead, they are large depresssions called calderas, often marked by a rim of higher land around the edges.​

The Yellowstone Supervolcano - Yellowstone National Park is located in the North West of the USA in the state of Wyoming, although it extends slightly into Montana and Idaho. It was the first National Park in the World and is a very volcanically active area due to the hotspot beneath it. Its location can be seen on the map below.

​Its Characteristics - Supervolcanoes are as their name suggests, super. They are much larger than normal volcanoes and when they erupt, they can change the many characteristics of Earth. They will eject at least 1,000km3 when they erupt compared to a normal volcano, which release around 1km3 of ash and rock. Unlike regular volcanoes, they do not have the usual cone like structure, rather they occur in large depressions called calderas. Calderas are formed when the magma chamber of a supervolcano collapses after an eruption leaving a large bowl shape in the ground. The magma chamber under Yellowstone is currently 80km long, 40km wide and 8km deep so if and when an eruption occurs, the caldera that is left will cover roughly the same area as London.Image courtesy of Wikipedia

​Likely Effects - When considering the Yellowstone supervolcano, one of, if not the largest supervolcano in the World, the effects could be catastrophic and change the face of the planet as we know it. Currently, there are 3,000 earthquakes in the area each year and along with various other changes, it has led scientists to worry that an eruption could occur soon, although this is very unlikely.

An eruption in the next couple of centuries is not expected. Some of the effects are predicted to be:​

10,000km2 of land erupted

25 mile high ash cloud

Everything within a 100 mile radius of the eruption will be destroyed

The ash in the atmosphere could lower global temperatures by 20°C

1,000 miles away, the layer of ash that will be deposited on the ground will be up to 10ft thick

Two thirds of the USA will be uninhabitable

87,000 could be killed

1 in 3 people affected would die

Huge impact on transport, energy, electricity, agriculture, and general production

The UK would receive the ash cloud 5 days after the eruption

The global economy will be placed under huge pressure and likely collapse due to the damage to the USA

Global climates would change, crops would fail and many people would die.​

Ash - US television networks would probably bring the first news of a Yellowstone super-eruption to the UK. It probably wouldn't take long for the first physical signs to appear.

Within 3-4 days, a fine dusting of ash could fall across Europe, according to a UK Met Office computer forecast commissioned by the BBC. The computer model predicts how ash would spread following a nine-day June eruption of 1000 cubic km of ash and gas from Yellowstone.

The model shows that the fallout from a Yellowstone super-eruption could affect three quarters of the US. The greatest danger would be within 1,000 km of the blast where 90 per cent of people could be killed. Large numbers of people would die across the country – inhaled ash forms a cement-like mixture in human lungs. Even the US East Coast could be paralysed by 1cm of ash.

Many people think that lava flows are the most dangerous volcanic hazards, but ash is often the biggest killer. Because supervolcanoes are highly explosive, much of the magma doesn't get a chance to become lava. Instead it is blasted into countless airborne ash particles – tiny scorching particles of jagged rock.

​Climate change - The most wide reaching effect of a Yellowstone eruption would be much colder weather. Volcanoes can inject sulphur gas into the upper atmosphere, forming sulphuric acid aerosols that rapidly spread around the globe. Scientists believe sulphuric aerosols are the main cause of climatic cooling after an eruption.Aerosols in the upper atmosphere would also scatter sunlight making the sky look like a cloudy winter morning all day long. The skies in Europe would appear red in the days after the eruption. To predict how the climate may be affected, the BBC relied on historic data from the Toba supervolcano in Indonesia about 74,000 years ago and computer model forecasts commissioned from the UK Met Office and the Max Planck Institute in Hamburg.Experts believe a Yellowstone eruption would inject 2,000 million tonnes of sulphur 40-50km above the Earth's surface. Once there it would take 2-3 weeks for the resulting sulphuric acid aerosols to cloak the globe – with devastating effects.

Global annual average temperatures would drop by up to 10 degrees, according to computer predictions. And the Northern Hemisphere could cool by up to 12 degrees. Experts say colder temperatures could last 6-10 years, gradually returning to normal.​Scientists predict that the Monsoon would fail as a result of even larger temperature changes in the Southern Hemisphere, causing mass starvation in the Asian countries that depend on these life-giving rains. Temperatures in Europe could be at least 5 degrees cooler the summer after the eruption.